Spiracle present. Snout short and blunt. Gill membranes joined to isthmus. Mouth transverse and lower lip with a split in the middle. The barbels are attached closer to the tip of snout than to the mouth and they are unfimbriated.
15-51 gill rakers, which are not fan-shaped, terminated by a single tip.
D: 27-51; A: 18-33 rays.
8-18 dorsal scutes; 24-50 lateral scutes and 6-13 ventral scutes. Between the rows of scutes there are numerous bony plates.
The colouration is greyish black, dirty green, or dark green dorsally. Laterally, it is usually greyish brown, and ventrally, grey or lemon. The juveniles are blue dorsally and white ventrally.

Caspian, Black and Azov Seas and the rivers that empty into them (Vlasenko et al., 1989).

Habitat and Biology

In the sea, the Russian sturgeon inhabits shallow waters of the continental shelf; in the rivers it remains at depths from 2 to 30 m. The larvae are found at considerable depths and in rapid currents.Besides the main diadromus form, a freshwater form that does not migrate downstream to the sea has been reported from various rivers.The Russian sturgeon is a bottom-dwelling mollusc-feeder (Corbulomya, Abra, Cardium, Nassa). They also readily consume crustaceans (shrimps and crabs) fishes (Engraulis encrasicolus, Sprattus sprattus and gobiids) and polychaetes. The main food items of juveniles are crustaceans, including mysids and corophiids, and polychaetes.The grat majority of the males begin to reproduce at an age of 11 to 13 years, while the equivalent age for the females is 12 to 16 years (Berg, 1948). In the Volga River, the males requires two to three years to reproduce again after spawning, while the females take four to five years. Usually, the spawnin run of this species into the rivers begin in early spring, reaches its peak in mid o later summer and ceases in late autumn. In the Volga River the spawning period extends from mid-May through early june. The spawning sites are gravel or stony beds at depths from 4 to 25 m.
Spawning at water temperatures between 8.9º C and 12º C.

Size

May reach 3 m, usually 110-140 cm. Reports of 4 m and about 600 kg may refer to Acipenser sturio.

Interest to Fisheries

The Russian sturgeon accounts for 40 % of the total acipenserid catch in the northern Caspian region, with a record of 11.980 tons in 1977.

Local Names

BULGARIA :
Ruska esetra .

FINLAND :
Venäjänsampi .

FRANCE :
Esturgeon du Danube .

GERMANY :
Russischer stör .

GREECE :
Storioni .

ITALY :
Storione danubiano .

NORWAY :
Rysk stor .

POLAND :
Jesiotr kolchidzki .

PORTUGAL :
Sturjao do Danúbio .

ROMANIA :
Nisetru .

RUSSIA :
Chernamorsko-azovskyi osetr .

SPAIN :
Esturión del Danubio .

SWEDEN :
Rysk stör .

TURKEY :
Karaka baligi .

UKRAINE :
Ruskii osetr .

UNITED KINGDOM :
Danube sturgeon .

USA :
Azov-Black sea sturgeon ,
Kura sturgeon .

Remarks

The status of some forms and subespecies of this species is now under study. Thus, Birstein & Bemis (1997) consider all intraspecies forms and subespecies of A. gueldenstaedtii, A. stellatus, A. nudiventris and of A. ruthenus invalids until detailed morphological and molecular studies of different forms within these species can be performed. Only if populations of the same species of sturgeons live in disjunct sea basins (e.g. Caspian and Black seas), could be considered as subespecies.